Fix launching shikane.

This was failing because the latest version of shikane opens the config file as read+write.

nix/configuration/roles/shikane/default.nix

@@ -37,6 +37,9 @@ in
     me.install.user.talexander.file = {
       ".config/shikane/config.toml" = {
         source = ./files/config.toml;
+        # Shikane opens with write permissions, so we need a regular file, not a symlink to the nix store.
+        method = "overwrite";
+        mode = "0644";
       };
     };
   };